The Netflix drama from brothers Matt and Ross Duffer has enlisted Sadie Sink and Dacre Montgomery as series regulars for season two, The Hollywood Reporter has learned. Additionally, breakout Joe Kerry (who plays Steve Harrington) and Noah Schnapp (Will Byers) have been promoted from recurring to series regulars.

Sink will play Max, a tough and confident girl whose appearance, behavior and pursuits seem more typical of boys than of girls in this era. She has a complicated history and is generally suspicious of those around her.

Montgomery will play Billy, Max's hyper-confident and edgy older step-brother. He steals girlfriends away from their boyfriends, is great at drinking games and drives a black Camaro. But lurking under his apparent charisma is a violent and unpredictable nature.

Details about the second season of the breakout 1980s drama remain sketchy, but the roles of Max and Billy are two of the three new faces expected to join the summer hit.

"There's definitely a handful of really compelling new characters this season, but absolutely servicing the core group first and foremost," executive producer Shawn Levy told THR. "Like the show itself, it's multigenerational new characters and really, really intriguing ones."

For her part, Sink began her professional acting career in the Broadway revival of Annie. She returned to Broadway as her follow-up with a role opposite Helen Mirren in Stephen Daldry's The Audience. Her small-screen work includes a regular role on NBC's American Odyssey and guest spots on Netflix's Unbreakable Kimmy Schmidt and FX's The Americans. She will next be seen in features The Glass Castle and The Bleeder. Sink is repped by Paradigm and Mara Entertainment.

Montgomery most recently wrapped Lionsgate's Power Rangers, where he plays the Red Ranger Jason Lee Scott. The actor is repped by WME, 3 Arts and Sloane Offer.

The heavily coveted roles come after the young Stranger Things cast became nearly overnight sensations following the critical adoration of the summer hit. The new stars hit the town over Emmy weekend and performed at the awards ceremony. Breakout Millie Bobby Brown (aka Eleven) recently signed with WME after being heavily courted by all the major agencies.